It is known that, as of today, artificial lighting systems for closed environments (“indoors”) are available which aim at improving the visual comfort experienced by users. In particular, lighting systems are known which simulate natural lighting, namely the type of lighting available in open-air environments (“outdoors”). The well-known characteristics of outdoor lighting depend on the interaction between light rays produced by the sun and the earth's atmosphere.
In pending European patent application EP2304480, which is incorporated by reference, a lighting system is described which includes a luminous source, aimed at producing visible light, and a panel containing nanoparticles. When in use, the panel receives light rays coming from the source and acts as a so-called Rayleigh diffuser, namely it diffuses light rays similarly to the earth's atmosphere in clear-sky conditions.
Additional details relative to the panel as in pending patent EP2304480 are described in pending European patent application EP2304478, which is incorporated by reference. Moreover, pending patent application EP2304480 describes various embodiments of the panel as well as various arrangements of the panel and the light source in respect to one another, aimed at simulating various conditions of natural lighting, such as for example lighting conditions that occur in nature in case of clear sky and i) sun at zenith or ii) sun close to the horizon.
The lighting system described in patent application EP2304480 simulates natural lighting in that it generates, inside the surrounding environment, direct light with low Correlated Color Temperature (“CCT”), which mimics sunlight and generates shadows in presence of lit objects; also, the lighting system described in patent application EP2304480 simulates natural lighting in that it casts diffused light with high CCT, which mimics skylight and generates shadows with a blue tinge. Nonetheless, such lighting system does not flawlessly reproduce the perceptive effects an observer would experience in presence of a sky-facing window. In particular, such lighting system does not lead an observer to experience the visual perception of unlimited depth of field.